import math

class Point():

    def __init__(self, x, y):
        self.x = x
        self.y = y

x1, y1, x2, y2 = [float(i) for i in input().split()]

point1 = Point(x1, y1)
point2 = Point(x2, y2)

x_dist = point1.x - point2.x
y_dist = point1.y - point2.y

dist = math.sqrt(x_dist ** 2 + y_dist ** 2)

print(dist) import math math class Point():

    def __init__(self, x, y):
        self.x = x
        self.y = y Point def __init__(self, x, y):
        self.x = x
        self.y = y __init__ self.x = x self.x self x x self.y = y self.y self y y self self x x y y float(i) for i in input().split() for i in input().split() i input().split() ().split () input split for i in input().split() float(i) float i x1, y1, x2, y2 = [float(i) for i in input().split()] x1 [float(i) for i in input().split()] y1 x2 y2 point1 = Point(x1, y1) point1 Point(x1, y1) Point x1 y1 point2 = Point(x2, y2) point2 Point(x2, y2) Point x2 y2 x_dist = point1.x - point2.x x_dist point1.x - point2.x point1.x point1 x point2.x point2 x y_dist = point1.y - point2.y y_dist point1.y - point2.y point1.y point1 y point2.y point2 y dist = math.sqrt(x_dist ** 2 + y_dist ** 2) dist math.sqrt(x_dist ** 2 + y_dist ** 2) math.sqrt math sqrt x_dist ** 2 + y_dist ** 2 x_dist ** 2 x_dist 2 y_dist ** 2 y_dist 2 print(dist) print dist y2 = [float(i) for i in input().split()] [float(i) for i in input().split()] y2 point1 = Point(x1, y1) Point(x1, y1) point1 x1, y1, x2, y2 = [float(i) for i in input().split()] [float(i) for i in input().split()] x1 x2, y2 = [float(i) for i in input().split()] [float(i) for i in input().split()] x2 y_dist = point1.y - point2.y point1.y - point2.y y_dist y1, x2, y2 = [float(i) for i in input().split()] [float(i) for i in input().split()] y1 dist = math.sqrt(x_dist ** 2 + y_dist ** 2) math.sqrt(x_dist ** 2 + y_dist ** 2) dist point2 = Point(x2, y2) Point(x2, y2) point2 x_dist = point1.x - point2.x point1.x - point2.x x_dist class Point():

    def __init__(self, x, y):
        self.x = x
        self.y = y class Point():

    def __init__(self, x, y):
        self.x = x
        self.y = y Point
import math

class Point():

    def __init__(self, x, y):
        self.x = x
        self.y = y

x1, y1, x2, y2 = [float(i) for i in input().split()]

point1 = Point(x1, y1)
point2 = Point(x2, y2)

x_dist = point1.x - point2.x
y_dist = point1.y - point2.y

dist = math.sqrt(x_dist ** 2 + y_dist ** 2)

print(dist)
